I am creating a OSD for a remote control airplane and I had a little problem when connecting a ME-1000RW GPS Module on my arduino, because the signal was too low, when searching for a solution for this, I found out that people usually use MAX232 to level the signal. But I found out that using a transistor and two resistors do the trick.

here is my test circuit:

before level up the signal, I was getting only tresh on the serial port.

The pullup resistors in your circuit seems a bit excessive - I would swap the position of the 1K and 10k resistors.

The use of a single transistor for "level" conversion suggests you're interfacing to RS-232 (as opposed to logic level TTL). Since your GPS apparently supports both TTL and RS-232, you may benefit from interfacing direct to the GPS logic level interface.

This doesn't match with your circuit, the issues you report or the datasheet. When you use a single transistor, you invert the logic level and so signals would no longer be compatible with the Arduino USART. It may work however with RS-232 levels (despite the excessive pullups as I mentioned).

It seems to me you're not doing what you think you are and so it may not be a good idea for others to follow your example.

void loop() // run over and over again{ if (mySerial.available()) { Serial.print((char)mySerial.read()); }

}

I have that datasheet you mentioned but its poorly written and it has a bunch of errors, even the PINOUTS are wrong. I placed this here because I've seen people that bought it having problems to communicate with are doing, and they just gave up.

Besides the voltage levels, there is a logic invertion. I would buy another module like EM-406 or locosys, but this was the only one available in Brazil.

I was browsing around and I found out that my GPS uses the same chipset used on the Sparkfun Venus GPS, the Venus634FLPX that I see many threads and none solved... If anyone is willing to try this please be careful, and try at your own risks, here is working great now.

and since I don't send anything to the GPS, I am only using the first portion of the schematic, a BC547 or BC548 and two resistors...

yes, my arduino nano is working at 5v. But you can also conect to a 3.3v if you use a chip that uses 3.3v logic levels. These Venus634FLPX based GPS are a pain. This was the only way mine worked... I only got trash from the serial before doing this... now I am getting real data: